• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.533-536
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• 2008

Recently, in Korea, there has been an increasing number of research papers published which are to improve durability of concrete, particularly by analyzing correlation between diffusivity of chloride and porosity/pore size distribution. In these studies, such test methods as mercury intrusion porosimetry(MIP), gas adsorption or image analysis method are used to analyze the microstructure of materials while MIP is most widely used for concrete. This study analyzes the results of porosity and pore size distribution of paste and concrete adding fly ash or blast furnace slag by using MIP equipment which is widely used for determining micro-porosity structure of cementitious materials. A variation in porosity and pore size distribution at the curing day 3, 7 and 28 has been observed by using MIP equipment for cement paste 35%, 40%, 45%, 50%, 55%, 60% of W/C when using $300kg/m^3$ of cement, 35%, 45%, 55% of W/C when replaced 60% with blast-furnace slag, and 35%, 45%, 55% of W/C when replaced 30% with fly ash. For long-term water cured normal OPC concrete and mixed concrete replaced 60% with blast-furnace slag powder, micro-structure of the sample has been analyzed by using MIP equipment when W/C indicated 40%, 45%, 50% respectively and the binder varied $300kg/m^3$, $350kg/m^3$, $400kg/m^3$, and $450kg/m^3$.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.5-16
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• 2010

Groundwater quality monitoring wells, which is over 2,000 in South Korea, were managed to observe groundwater quality since the early 1990s. Groundwater was sampled and analyzed biannually from 781 monitoring wells located in the areas with a high possibility of pollution. The average concentrations of cyanide, mercury, phenols, hexavalent chromium, trichloroethylene, tetrachloroethylen, and 1.1.1-trichloroethane for 12 years' data of detected cases were above the groundwater quality standard, but the average concentrations of the general quality items such as pH, electric conductivity, nitrate-nitrogen, and chloride, are below the standard. To compare a quality trend for each land-use type of the monitoring site, Sen's method is used for four quality items; chloride, nitrate-nitrogen, pH, and electric conductivity. The upward trend for these items is remarkable in urbideareas and industrial complexes and this trend continues still strongly after 2001. The deviation in a trend slopes of monitoring wells becomes bigger in the mid-2000s. In conclusion, trend analysis using existing monitoring data cidebe effective to forecast the future water quality condition and the solid action to protect groundwater quality should be done in advance using a result of trend analysis.

• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.233-238
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• 1985

The non-porous and porous polystyrene divinylbenzene copolymers were prepared by the suspension polymerization method. The non-porous aminated polystyrene divinylbenzene, N-APSTDVB and the porous aminated polystyrene divinylbenzene, P-APSTDVB of 50∼100mesh size weakly basic anion exchanger were synthesized by chloromethylation followed by amination with methylamine. The functional groups of these synthesized anion exchangers were confirmed by their infrared spectra. The maximum capacity of these exchangers was 4.86meq/g. Pore volume and pore spectra were determined with a mercury porosimeter. The pore volume of P-PSTDVB increased with increasing X$_{diluent}$ at 30% of divinylbenzene. However, the pore volume of P-PSTDVB increased with increasing volume percent of divinylbenzene at constant mole fraction of diluent, X$_{diluent}$ of 0.5. The pore volume of synthesized copolymer and anion exchanger at 8% divinylbenzene and 0.5X$_{heptane}$ decreased as follows; P-PSTDVB 〉P-APSTDVB 〉N-PSTDVB. This result was attributed to the possibility that the pore volume were reduced by amination reactions. The distribution coefficients of boric acid on the N-APSTDVB anion exchanger in various concentrations of alcohol water solutions showed that as alcohol concentration increased, the distribution coefficients values decreased due to the reduced concentration of H$_2$BO$_3^-$.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.21-31
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• 1968

The appearance rates of antipyrine and urea into cerebrospinal fluid from blood were studied in the rabbits which were in the state of hypotension and of high permeability in the capillary beds following injection of histamine. The alteration in the distribution of electrolytes among various compartments of the brain and the permeability characteristics in the blood-cerebrospinal fluid barrier were also observed. Adult male rabbits, weighing around 2 kg, were used. Twenty four rabbits were divided into 3 groups. Besides the control group, histamine treated rabbits were categorized into 2 groups. $H_1$ consisted of the rabbits showing moderate responses to histamine and ranging from 62 to 80 mmHg in their mean anterial blood pressure. The animals which belong to $H_2-group$ showed severe responses to histamine and the mean anterial blood pressures dropped to 30-50 mmHg. Animals were anesthetized with nembutal, 30mg/kg i.v. The mean arterial blood pressure was read by means of the mercury manometer connected to the femoral artery. The animals, treated with histamine, were kept in hypotensive state at least for 40 minutes before the administration of the test-substances. The test-substances, 300 mg of urea and 200 mg of antipyrine, were dissolved in 3 ml of distilled water and were injected into the ear vein of the rabbit. After 10 minutes elapsed arterial blood sample was taken from the femoral artery and cerebrospinal fluid from the cisterna magna. Brain tissues were also analysed with respect to electrolytes in order to observe the disturbances in the electrolytes balance as well as in the function of the central nervous system. The results obtained were as follow: 1. The ratio of antipyrine concentration in cerebrospinal fluid to that of arterial blood plasma, that was the distribution ratio, was close to unity, revealing a well established equilibrium between the compartments of blood and cerebrospinal fluid in 10 minutes. In other words, there was no diffusion barrier with regard to antipyrine. The ratios over unity which were frequently seen in the histamine treated animals were attributable to the early penetration of the substance into the cerebrospinal fluid. 2. The appearance rates of urea into the cerebrospinal fluid in the histamine treated rabbits were higher in comparison with those of in the control animals. The increasing tendency in the rates was particularly remarkable in the $H_2-group$, showing the enhanced penetration of urea across the boondary. 3. In the htisamine treated $H_2-group$ the concentration of potassium in the blood plasma and cerebrospinal fluid well exceeded the control values and showed 8.5 and 9.0 mEq/l in average, respectively. Simultaneous drops in the brain tissue water were noticed, suggesting the leakage of intracellular potassium. 4. There was a coincidence in the rising pattern of potassium in the blood plasma and in the cerebrospinal fluid of $H_2-group$ and at least partial removal of the blood-cerebrospinal fluid barrier with respect to potassium was suggested in these animals. 5. The concentration of sodium in the blood plasma or in the cerebrospinal fluid showed no significant changes following histamine injection. However, sodium in the brain tissue revealed slight elevation in the histamine treated groups. 6. The ratios of the concentrations of potassium to those of sodium, [K]/[Na] in the brain tissues, were 1.92 in the control 1.82 in the $H_1$ and 1.52 in the $H_2-group$, respectively. The marked drop in the $H_2-group$ might represent neural dysfunction in the extremely hypotensive rabbits.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.9-17
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• 2015

In order to elucidate the current state of marine pollution of heavy metals around major shipyards in Korea, seawater samples were collected at eleven sampling stations and four control stations around 4 major shipyards located in the southeastern coast of Korea in summer 2010, and 6 kinds of metals such as copper(Cu), zinc(Zn), iron(Fe), cadmium(Cd), lead(Pb) and mercury(Hg) in seawater samples were analyzed. The analyses of heavy metals in seawater showed that the mean Cu concentrations in seawater around 4 major shipyards were in the range of $0.817{\sim}1.638{\mu}g/L$ which were lower than Korean environmental standards of $20{\mu}g/L$ for the protection of human health(PHH) and of $3{\mu}g/L$ for short-term protection of marine ecosystem(SPME) but higher than Cu concentration at control station by a factor of up to 2.75. The mean Zn concentrations were in the range of $0.228{\sim}0.567{\mu}g/L$ which were lower than Korean environmental standards of $100{\mu}g/L$ for PHH and $34{\mu}g/L$ for SPME but higher than Zn concentration at control station by a factor of up to 5.91. The mean Fe concentrations were in the range of $3.332{\sim}7.410{\mu}g/L$ which were higher than Fe concentration at control station by a factor of up to 6.75. The mean Cd concentrations were in the range of $0.013{\sim}0.028{\mu}g/L$ which were lower than Korean environmental standards of $10{\mu}g/L$ for PHH and $19{\mu}g/L$ for SPME but higher than Cd concentration at control station by a factor of up to 2.33. The mean Pb concentrations were in the range of $0.007{\sim}0.126{\mu}g/L$ which were lower than Korean environmental standards of $50{\mu}g/L$ for PHH and $7.6{\mu}g/L$ for SPME. The mean Hg concentrations were in the range of $0.002{\sim}0.004{\mu}g/L$ which were lower than Korean environmental standards of $0.5{\mu}g/L$ for PHH and $1.8{\mu}g/L$ for SPME. Although the concentrations of metals such as Cu, Zn and Fe which were used in shipbuilding works were lower than Korean environmental standards for PHH and SPME, the fact that the concentrations of Cu, Zn and Fe at sampling stations around major shipyards were higher than those at control stations implies that the works in shipyards had some effects on marine water quality around shipyards. Therefore, marine environment management such as the prevention and control of the discharge of various pollutants from shipyards is required on national level.

• Membrane Journal
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• v.21 no.2
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• pp.118-126
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• 2011

A method of light pre-irradiation, one of methods modifying hydrophobic surface to hydrophilic surface in a membrane, was proposed to overcome the drawback of previous methods such as blending, chemical treatment and post-irradiation, Process of membrane preparation in the study was comprised of 4 parts as follows: firstly process of precursor preparation to introduce hydrophilic nature under atmosphere and aqueous vapor by irradiating electron beam (EB), secondly process of dope solution preparation to cast on non-woven fabrics, thirdly process of casting to prepare membrane and finally process of coagulation in non-solvent to form porous structure. The merit of this method might show simple process as well as homogenous modification compared to previous methods. To carry it out, precursor was prepared by irradiating EB to powder PVDF at 75~125 K Gray dose. Precursor prepared was analyzed by FTIR, EDS and DSC to confirm the introduction of hydrophilic function and its mechanism. From their results, it was inferred I conformed that hydrophilic function was hydroxy1 and it was introduced by dehydrozenation. Hydrophilicity of membranes prepared was evaluated by contact angle (pristine PVDF : $62^{\circ}$, 125 K Gray-PVDF$13^{\circ}$). Porosity was evaluated by mercury intrusion method, simultaneously morpholoy and surface pore size were observed by SEM phothographs. The result showed the trend that more dose of EB led to smaller pore size and to lower porosity (pristine PVDF : 82%, 125 K Gray-PVDF : 63%). Trend of water permeability was similar to result above (pristine PVDF : 892 LMH, 125 K Gray-PVDF : 355 LMH).

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.613-621
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• 2007

Due to the increasing significance of durability, much researches on carbonation, one of the major deterioration phenomena are carried out. However, conventional researches based on fully hardened concrete are focused on prediction of carbonation depth and they sometimes cause errors. In contrast with steel members, behaviors in early-aged concrete such as porosity and hydrates (calcium hydroxide) are very important and may be changed under carbonation process. Because transportation of deteriorating factors is mainly dependent on porosity and saturation, it is desirable to consider these changes in behaviors in early-aged concrete under carbonation for reasonable analysis of durability in long term exposure or combined deterioration. As for porosity, unless the decrease in $CO_2$ diffusion due to change in porosity is considered, the results from the prediction is overestimated. The carbonation depth and characteristics of pore water are mainly determined by amount of calcium hydroxide, and bound chloride content in carbonated concrete is also affected. So Analysis based on test for hydration and porosity is recently carried out for evaluation of carbonation characteristics. In this study, changes in porosity and hydrate $(Ca(OH)_2)$ under carbonation process are performed through the tests. Mercury Intrusion Porosimetry (MIP) for changed porosity, Thermogravimetric Analysis (TGA) for amount of $(Ca(OH)_2)$ are carried out respectively and analysis technique for porosity and hydrates under carbonation is developed utilizing modeling for behavior in early-aged concrete such as multi component hydration heat model (MCHHM) and micro pore structure formation model (MPSFM). The results from developed technique is in reasonable agreement with experimental data, respectively and they are evaluated to be used for analysis of chloride behavior in carbonated concrete.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.407-414
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• 2010

Until now, the pore size distribution, PSD, of soil profile has been calculated from soil moisture characteristic data by water release method or mercury porosimetry using the capillary rise equation. But the current methods are often difficult to use and time consuming. Thus, in this work, theoretical framework for an easy and fast technique was suggested to estimate the PSD from unsaturated hydraulic conductivity data in an undisturbed field soil profile. In this study, unsaturated hydraulic conductivity data were collected and simulated by the variation of soil parameters in the given boundary conditions (Brooks and Corey soil parameters, ${\alpha}_{BC}=1-5L^{-1}$, b = 1 - 10; van Genuchten soil parameters, ${\alpha}_{VG}=0.001-1.0L^{-1}$, m = 0.1 - 0.9). Then, $K_s$ (1.0 cm $h^{-1})$ was used as the fixed input parameter for the simulation of each models. The PSDs were estimated from the collected K(h) data by model simulation. In the simulation of Brooks-Corey parameter, the saturated hydraulic conductivity, $K_s$, played a role of scaling factor for unsaturated hydraulic conductivity, K(h) Changes of parameter b explained the shape of PSD curve of soil intimately, and a ${\alpha}_{BC}$ affected on the sensitivity of PSD curve. In the case of van Genuchten model, $K_s$ and ${\alpha}_{VG}$ played the role of scaling factor for a vertical axis and a horizontal axis, respectively. Parameter m described the shape of PSD curve and K(h) systematically. This study suggests that the new theoretical technique can be applied to the in situ prediction of PSD in undisturbed field soil.

• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.2
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• pp.19-29
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• 1994

A large volume of paper mill sludge(PMS) is produced every day from paper industries after treatments of waste water and it costs too much to dispose of the sludge. Since PMS consists mostly of biodegradable organic matter, cellulose, it is desirable to recycle it by proper treatments such as composting. In this study, experiments were conducted using a small scale reactor(12l) to establish optimum conditions for efficient composting of PMS of which initial pH, C/N ratio, and moisture content were 7.1, 28~30, and 60~65%, respectively. No heavy metals such as mercury, cadmimum, and lead were not detected in the PMS. Various levels of forced aeration, 1 minute aeration per every 30, 60, 120, 240, and 480 minutes were applied and 1 minute aeration per 60 and 120 minutes found to be proper for composting of 8l PMS in this system. Relationship between $CO_2$ production and temperatures was positively correlated with r> 0.82 suggesting that the normal decomposition of PMS by microorganisms occurred. However, under the condition of aeration interval over than 240 minutes, a negative relationship between two parameters was found indicating the occurrence of abnormal(maybe anaerobic) degradation. The amount of added nitrogen also affected composting of PMS resulting in the increase of $CO_2$ production and temperature. Semi-field tests using 100kg PMS in a static pile sysem showed that PMS could be composted efficiently under optimal environmental conditions. The parameters determining efficiency of composting such as C/N ratio, aeration, moisture content, and pH need to be monitored.

• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.248-256
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• 2021

A total of 120 samples corresponding to 12 categories of dried processed fishery products distributed in Gyeonggi-do were examined for radioactivity contamination (¹³¹I, ¹³⁴Cs, ¹³⁷Cs) and heavy metals (lead, cadmium, arsenic, and mercury). One natural radioactive material, ⁴⁰K, was detected in all products, while the artificial radioactive materials ¹³¹I, ¹³⁴Cs and ¹³⁷Cs were not detected at above MDA (minimum detectable activity) values. The detection ranges of heavy metals converted by biological basis were found as follows: Pb (N.D.-0.332 mg/kg), Cd (N.D.-2.941 mg/kg), As (0.371-15.007 mg/kg), Hg (0.0005-0.0621 mg/kg). Heavy metals were detected within standard levels when there was an acceptable standard, but the arsenic content was high in most products, although none of the products had a permitted level of arsenic. In the case of dried processed fishery products, there are products that are consumed by restoring moisture to its original state, but there are also many products that are consumed directly in the dry state, so it will be necessary to set permitted levels for heavy metals considering this situation in the future. In addition, Japan has decided to release contaminated water from the Fukushima nuclear power plant into the ocean, so there is high public concern about radioactivity contamination of food, including fishery products. Therefore, continuous monitoring of various food items will be necessary to ease consumers' anxiety.